Should they be there? Oh, my word yes. Politics is really a set of happenings that determine who will be in charge and what sort of things, based on character traits, will happen when/if they achieve their goal. The character traits are way more important that what they actually promise. Promises are words and words can be denied. Who a person is, inside, is much more indicative.
Frex, in Darkspire Reaches, the Angressi emperor decrees all witches must die. Now it isn’t really as simple as suddenly deciding he doesn’t like them. There is always cause before effect and he has a secret and is none too secure on his throne. He knows witches/wise women can scry, (look into the past and the future through magical means), as his own cousin he tried to have arrested had this skill. He thought he had dealt with the issue at that time, since she disappeared. Whispers have started, so he must remove all of these people with magic. His actions start a series of events, so again effect generated by a cause. In this case, the cause was fear and guilt. He needed to protect his position, which would have become jeopardised if his secret had been revealed, which is part of the guilt. Character traits are everything, for had he been a wise and kind ruler no one would be digging around for a way to displace him.
Very often the motivation is grounded in politics. Something important needs to happen for the continuation or the replacement of a set of circumstances. They are grounded into our lives so, by extension, are part of life that must be present in full in a story to create the living, believability factor.